This invention relates to liquid ring gas pumps.
Liquid ring gas pumps generally require a substantially continuous inflow of fresh or recirculated pumping liquid (sometimes referred to as "make-up" pumping liquid) to replace the pumping liquid that is normally lost via the gas discharge port. This flow of pumping liquid through the pump is also used to absorb some of the heat generated in the pump, thereby preventing the pump from overheating. A substantially continuous inflow of make-up pumping liquid is therefore essential to successful operation of a liquid ring pump.
In many liquid ring pump installations, the major portion of the pumping liquid inflow is pumping liquid that has been recirculated from the discharge port of the pump. In general, such recirculating flow must be at least partially propelled by a separate liquid pump. This increases the cost and complexity of the system. It also decreases the reliability of the system to the extend that the separate liquid pump is subject to failure. Even if such a separate liquid pump is not required to maintain pumping liquid recirculation during normal operation of the liquid ring pump, it may be difficult or impossible to start the liquid ring pump successfully without a separate liquid pump to initiate the flow of pumping liquid into the pump during start-up.
In view of the foregoing, it is an object of this invention to provide liquid ring pumps that are self-priming, i.e., liquid ring pumps that can themselves initiate and sustain a recirculating flow of pumping liquid partly external to the pump (and create a properly formed internal liquid ring utilizing this liquid) without the need for a separate liquid pump.
It is another object of this invention to provide methods for operating liquid ring pumps so that they are self-priming, particularly during start-up.
As shown in German Pat. No. 258,483, it is known that the volumetric efficiency of liquid ring gas pumps can be improved by providing a conduit for causing gas that would otherwise be carried over from the compression zone to the intake zone ("carry-over" gas) to instead bypass the intake zone. (As used herein, the term "gas" refers to the largely gaseous and/or vaporous medium being pumped by the liquid ring pump.) In practice, however, it is extremely difficult or impossible to cast or otherwise form bypass conduits of the type shown in the German patent in the port members of conically or cylindrically ported liquid ring pumps.
It is therefore another object of this invention to provide improved bypass conduit configurations for conically and cylindrically ported liquid ring pumps.
It is still another object of this invention to provide liquid ring pumps having both a bypass conduit and self-priming operation.
It is yet another object of this invention to provide methods of operating liquid ring pumps so that the bypass conduit of the pump additionally renders the pump self-priming.